Compositions and methods for dying natural fibers with natural dyes to ensure color (hue and shade)-match consistency

ABSTRACT

This invention discloses novel and nonobvious compositions and methods suitable for the dyeing of natural fibers with natural dyes that ensure shade-match consistency.

BACKGROUND

The use of natural dyes for the dyeing of natural yarns and fabrics has been known since the beginning of recorded history. However, consistent, uniform hue and shade-matching of dyed materials from batch-to-batch has eluded even the most practiced artisan. Consistent hue and shade-matching is the most difficult to achieve both within a batch and between batches. Prior art attempts to solve this problem between batches have failed. The dyeing industry has turned to synthetic dyes because they afford greater control over the dyeing process and can achieve the desired hue and shade-match consistency. However, the production and use of synthetic dyes results in vast quantities of toxic waste materials that need to be managed. Still, even when faced with the waste problem caused by the use of synthetic dyes, the commercial dyeing industry has rejected the use of natural dyes because of the aforementioned inconsistency in hue and shade-matching, among other challenges. Thus, what is needed are new compositions and methods for dyeing natural fibers with natural dyes that achieve hue and shade-matching on a commercial scale and result in fewer rejects and greatly reduced waste when compared to synthetic dyeing processes.

SUMMARY OF THE INVENTION

The present invention provides compositions and methods for the dyeing of natural fibers (yarns, fabrics and garments) with natural dyes while providing for uniform hue and shade-match in the same batch and between batches. While not wishing to be bound by theory, it is believed that the use of ferrous sulfate solution at the disclosed concentrations and processes, together with the use of loosely wound yarn packages, provides for enhanced dye penetration (take-up) by the yarn package enabling uniform package dyeing. The inclusion of the natural dyestuff solution spectrophotometer and the yarn package spectrophotometer provides system inputs enabling precise hue and shade-matching between batches with minimal dye waste.

The present invention contemplates a process for dying yarn produced from a natural fiber using a natural dyestuff, the process comprising: providing a loosely wound yarn package having a yarn density of less than about 0.85 g/cm³; providing a natural dyestuff solution; providing a tank that will accommodate the yarn package and an initial volume of the natural dyestuff solution; providing a yarn package spectrophotometer and a natural dyestuff solution spectrophotometer; contacting the yarn package and the initial volume of natural dyestuff solution within the tank under conditions appropriate for uptake of the natural dyestuff by the yarn; monitoring absorbance of the yarn package by the yarn package spectrophotometer and the natural dyestuff solution by the natural dyestuff solution spectrophotometer; supplementing the initial volume of natural dyestuff solution with an appropriate quantity of the natural dyestuff solution, as needed, to achieve a condition wherein the yarn package spectrophotometer detects absorbance at a desired wavelength and the natural dyestuff solution spectrophotometer detects absorbance consistent with a substantially depleted natural dyestuff solution; replacing the dyestuff solution with a solution comprising ferrous sulfate at a concentration of about 1% to 8% by weight of the dry weight of goods (WOG) to be dyed; and contacting the yarn package with the ferrous sulfate comprising solution for a period of time suitable to fix the dyestuff to the fibers.

The present invention further contemplates that the yarn package is contacted with a mordant solution prior to being contacted with the dyestuff solution and wherein the mordant solution is removed before the yarn package is contacted with the dyestuff solution. The present invention further contemplates that the natural fiber is selected from the group consisting of wool or cotton. The present invention further contemplates that the natural dyestuff is selected from the group consisting logwood, cochineal, madder, cutch, myrobalan, hematine, pomegranate, and chestnut. The present invention further contemplates that the ferrous sulfate solution is at a concentration of about 2% to 6% by weight of the dry WOG to be dyed. The present invention further contemplates that the process comprises filtering the natural dyestuff solution prior to use. The present invention further contemplates that the natural dyestuff solution is filtered through a 100-1000 nm filter.

The present invention contemplates a process for dying fabric produced from a natural fiber using a natural dyestuff, the process comprising: providing a natural dyestuff solution; providing a tank that will accommodate the fabric and an initial volume of the natural dyestuff solution; providing a fabric spectrophotometer and a natural dyestuff solution spectrophotometer; contacting the fabric and the initial volume of natural dyestuff solution within the tank under conditions appropriate for uptake of the natural dyestuff by the yarn; monitoring absorbance of the fabric by the fabric spectrophotometer and the natural dyestuff solution by the natural dyestuff solution spectrophotometer; supplementing the initial volume of natural dyestuff solution with an appropriate quantity of the natural dyestuff solution, as needed, to achieve a condition wherein the fabric spectrophotometer detects absorbance at a desired wavelength and the natural dyestuff solution spectrophotometer detects absorbance consistent with a substantially depleted natural dyestuff solution; replacing the dyestuff solution with a solution comprising ferrous sulfate at a concentration of about 1% to 8% by weight of the dry weight of goods (WOG) to be dyed; and contacting the fabric with the ferrous sulfate comprising solution for a period of time suitable to fix the dyestuff to the fibers.

The present invention further contemplates that the fabric is contacted with a mordant solution prior to being contacted with the dyestuff solution and wherein the mordant solution is removed before the fabric is contacted with the dyestuff solution. The present invention further contemplates that the natural fiber is selected from the group consisting of wool or cotton. The present invention further contemplates that the natural dyestuff is selected from the group consisting logwood, cochineal, madder, cutch, myrobalan, hematine, pomegranate, and chestnut. The present invention further contemplates that the ferrous sulfate solution is at a concentration of about 2% to 6% by weight of the dry WOG to be dyed. The present invention further contemplates filtering the natural dyestuff solution prior to use. The present invention further contemplates that the natural dyestuff solution is filtered through a 100-1000 nm filter. The present invention further contemplates that the fabric is selected from a group consisting of woven and non-woven fabric.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic diagram of one embodiment of the device used in the dying of natural fibers with natural dyes by the methods of the present invention.

FIG. 2 shows a dyed 1 pound cotton yarn package died berry color.

DESCRIPTION OF THE INVENTION

The methods described herein enable natural dyeing of natural fibers, on a commercial scale, with the consistent and reproducible hue and shade-matching required by garment retailers. The term “color” refers to the break-down of the color with regard to the primary (red, blue and yellow), secondary (green, purple and orange) and tertiary colors. The term “shade” refers to how dark the color is. In dyeing, color is determined by the dye mix and shade is determined by the uptake of the dye into the fiber. The ability to shade-match the dyeing of natural fibers using natural dyes consistently has been previously unachievable on any scale. For example, U.S. Pat. No. 5,651,795 describes the shade-matching problem in column 1, lines 56-60 stating “it is almost impossible using known techniques to obtain the same dye shade twice in succession with natural dyes, even using the same method.”

The term “natural dying,” as used herein, refers to the dying of natural fibers with natural dyes. Natural fibers include, for example, protein fibers such as wool and cellulose fibers such as cotton. Wool is a textile fiber obtained, for example, from sheep and certain other animals, including cashmere from goats, mohair from goats, qiviut from muskoxen, angora from rabbits, other types of wool from camelids, and others known in the art. Examples of cellulose fibers include, cotton from the cotton plant, linen from the flax plant, jute, hemp, papaya, sisal (agave), milkweed and others known in the art. In the present specification, the terms fiber, yarn, garment and fabric all refer to a natural fiber article (i.e., the material(s)) being dyed and may be used interchangeably. The term fabric shall refer to woven and non-woven fabric as well as items made from fabric such as garments, bags, tarps, etc.

Natural dyes are dyes obtained from natural source materials such as plants, invertebrates, minerals and animal products such as urine. The source material must be processed to isolate and concentrate the dye. Many examples of natural dyes are known in the art and are discussed below. Natural dyes, such as indigo, from the indigofera plant, and madder, from the madder root, have been used since the beginning of recorded history. However, shading-matching on a commercial scale has been unattainable by those of skill in the art. This is because, as one synthetic dye manufacturer states, the color-giving molecules used for dyeing have not been “specifically designed by nature” for transfer to a substrate. Because of these problems, large scale dyeing (i.e., commercial scale dyeing) has turned to the use of synthetic dyes.

The unexpected success of the present invention to provide for shade-matched dying of natural fibers with natural dyes is based on several inventive concepts. These inventive concepts of the present invention relate to both package or yarn dyeing and fabric or piece dyeing. For package dyeing, a loose winding of the yarn on the tube on which the yarn will be dyed. The yarn on the tube is referred to in the art as a “package.” While not wishing to be bound by theory, it is believed that loosely wound yarn allows the dye and dyestuff solution to reach and penetrate all fibers of the yarn. The looseness or tightness of the yarn in a package is measured in terms of “package density.” A tighter wind has a higher package density. A looser wind has a lower package density. The yarn package of the present invention has a package density of less than about 1.5 g/cm³, less than about 0.85 g/cm³, less than about 0.75 g/cm³, less than 0.65 g/cm³, less than 0.50 g/cm³, to about 0.10 g/cm³. For piece dyeing, it is critical that the liquor ratio be maintained from about 3:1 to about 10:1.

The inventive concepts of the present invention also include the use of at least one and preferably two spectrophotometers to monitor the dyeing process. The first spectrophotometer (the yarn or fabric spectrophotometer) is positioned to monitor the yarn or fabric color in the dyeing vat (or kier) or tank. Feedback from the first spectrophotometer is used to monitor the yarn or fabric color and thereby control the dying process. The second spectrophotometer (the dyestuff spectrophotometer) is positioned in the recharge kier or dye bath vat or tank and used to measure the concentration of dyestuff in the dyestuff solution returning from the dyeing kier and/or in the dye bath tank in the case of package dyeing and in the case of piece dyeing. For package dyeing the recharge kier is used to replenish the dyestuff solution as needed to ensure proper and consistent dying of the fibers on the package.

In an alternative embodiment, either the first or the second spectrophotometers can be used independently. In a preferred embodiment of this embodiment the spectrophotometer in the dyeing vat is used to monitor the color of the yarn or fabric being dyed. The yarn or fabric is removed upon obtaining the desired shade and hue. However, if desired, the spectrophotometer in the recharge kier (tank) can be used independently to monitor the dyeing process via the depletion of the dye in the dye solution. This option may be preferred, for example, to ensure that the system is run to depletion prior to the use of a different dye solution.

These inventive concepts also include the incorporation of a ferrous sulfate solution at the disclosed concentrations into the dyeing process. While not wishing to be bound by theory, it is believed that ferrous sulfate acts to fix, secure, bind, set, intercalate or otherwise hold the dye to the yarn fibers. Herein we refer to the ferrous sulfate as a fixative. Whereas a mordant (see, below) acts to prepare fibers for attachment of dye (much like a primer for paint) a fixative secures dye already loosely attached to the fiber thereby ensuring that it does not come off during wearing or washing, for example. In the present dyeing process, ferrous sulfate solution is used after the dyeing of the fibers and removal of the dyestuff solution. Ferrous sulfate is colorless or essentially colorless when dissolved in water. Ferrous sulfate treatment of the material causes a slight darkening of the color shade. The degree of darkening is consistent between batches or runs. The darkening of the color shade is figured into the final color shade achieved during the dyeing step so that the desired color shade is obtained after the treatment of the material with ferrous sulfide. Ferrous sulfate is used in the present invention at from 1% to 8% weight of goods (WOG), 2%-6% WOG, 2.5%-4% WOG or about 3% WOG. Weight of goods refers to the dry weight of material (for example, yarn, cloth or garment) to be dyed. The ferrous sulfate step of the present invention may also be referred to as the fixing or fixative step.

In some instances the dyeing process of the present invention also includes the use of a mordant. A mordant provides for enhanced dye penetration (take-up) by the yarn package enabling uniform package dyeing. A mordant is a substance used to set dyes on fabrics by forming a coordination complex with the dye which then attaches to the fabric. Examples of mordants for natural dyes are alum (potassium aluminum sulfate), aluminum acetate (for use when dyeing cotton), chrome (potassium dichromate or potassium bichromate), blue vitriol (copper sulfate), ferrous sulfate, stannous chloride, sodium dithionite or sodium hydrosulfite, ammonium hydroxide, cream of tartar (potassium bitartrate), “Glauber's salt” (sodium sulfate), lime, lye (sodium hydroxide), oxalic acid, tannic acid, urea, vinegar (acetic acid) and washing soda (sodium carbonate, also known as soda ash). The use of ferrous sulfate in the context of the present invention as a fixative is different than the use of ferrous sulfate as a mordant in the prior art. Preferred mordants for use in the present invention for dyeing wools are aluminum sulfate (at about 10 5-about to 25%) and cream of tartar (at about 3% to about 10%). Preferred mordants for use in the present invention for dyeing cottons (and other cellulose fibers) are aluminum acetate (at about 10 0-about to 20%) and cream of tartar (at about 3% to about 10%). Some dyes, such as indigo, do not typically require the use of a mordant. Mordant(s), if used, are used at about 160 to about 210° F., about 170-about 205° F., about 180-about 200° F. or about 190° F. Mordants used for about 15-120 minutes, 30-90 minutes, 45-75 minutes or about 60 minutes. After mordant treatment and prior to dyeing the mordant solution is removed from the material to be dyed and the material is rinsed and dried prior to dyeing.

Another mordant procedure that is compatible with the present invention is as follows. Preferably, this procedure is used with dyeing of cotton, especially, but not limited to, goldenrod, rock salt and black dyes. First, goods and/or yarn is scoured, if desired. Tannin is dissolved in boiling water. The dissolved tannin is added slowly into the bath (tank) while bringing bath temperature to 120° F. for 45 minutes for a final concentration of 2% tannin. Although the present invention is not limited by theory, it is believed that tannin helps with color fastness. Tannin may darken with higher temperatures affecting lighter colors. This is taken into account when dyeing. The batch is drained, the fabric/yarn is rinsed and the tank is refilled with 8% aluminum acetate in hot water 100° F. for 60 minutes. The tank is drained and the fabric/yarn is processed with the procedures of the present invention for dyeing.

In one embodiment of the methods of the present invention, for package dyeing, the dyestuff solution is pumped from the recharge kier into the dyeing kier. The yarn package comprises the yarn wound loosely around a center tube (the tube). The tube is porous (perforated) to permit fluid flow through the tube and then through the yarn. The dyestuff solution is pumped in to the center of the package tube and the dyestuff flows through the tube pores and into and over the yarn. Once the dye stuff solution passes through the yarn package, the used dyestuff solution flows back into the recharge kier for recharging. The process is continued until the yarn has obtained the desired color (hue and shade). With the use of two spectrophotometers, the first spectrophotometer provides feedback for the yarn color while the second spectrophotometer is used to regulate the concentration of dye in the dyestuff flowing from the recharge kier into the dyeing kier. Thus, the process can be controlled in such a way that the dyestuff solution is depleted of dyestuff as the yarn reaches the desired color (hue and shade). In this manner, waste is minimized and over or under dyeing of the yarn is prevented. In one embodiment, the temperature of the dyestuff is from about 160 to about 210° F., about 170-about 205° F., about 180-about 200° F. or about 190° F. The dye stuff is used for about 15-120 minutes, 30-90 minutes, 45-75 minutes or about 60 minutes.

After dyeing, the dyestuff solution is removed and the yarn is contacted with the ferrous sulfate solution disclosed above. The ferrous sulfate solution is used at about 160 to about 210° F., about 170-about 205° F., about 180-about 200° F. or about 190° F. The ferrous sulfate solution is used to fix the dye to the yarn for about 15-120 minutes, 30-90 minutes, 45-75 minutes or about 60 minutes. After fixation, the ferrous sulfate solution is removed.

After fixation with the ferrous sulfate solution, the yarn fibers may be measured to confirm color shade match, washed, dried and inspected. A final color shade check can be performed if desired.

In some embodiments, the flow of the mordant solution, dyestuff solution or ferrous sulfate solution can be reversed. Although not necessary, reverse flow can help ensure even preparation of the fibers, dyeing of the fibers and/or fixing of the dye to the fibers by having the desired solutions flow over and into the yarn fibers from the opposite direction. Further, the flow may be run in forward or reverse to provide for rinsing of dyed yarn after the dyeing process is complete.

For piece dyeing (e.g., fabrics and garments) the dyestuff solution is pumped from the charge/recharge tank into the dyeing tank. The fabric comprises the knitted or woven fibers (either tubular or open width). The fabric is inserted into a jet machine via the venturi with the ends sewn together to create a full loop so that the entire length can be run through the dye bath tank up to about 10 yards per minute. One of ordinary skill in the art will be able to determine the appropriate speed to ensure desired dyeing result without undue experimentation. A jet machine is a dyeing machine known to those of ordinary skill in the art for dyeing piece material (i.e., fabrics and the like). The dyeing process is continued as established by the procedure (typically 45 to 60 minutes at temperature or until the fabric has obtained the desired color (hue and shade)). With the use of two spectrophotometers, the first spectrophotometer provides feedback for the fabric color while the second spectrophotometer is used to regulate the concentration of dye in the dye bath. Thus, the process can be controlled in such a way that the dyestuff solution is depleted of dyestuff as the fabric reaches the desired color (hue and shade). In this manner, waste is minimized and over or under dyeing of the piece is prevented. In one embodiment, the temperature of the dyestuff is from about 160 to about 210° F., about 170-about 205° F., about 180-about 200° F. or about 190° F. The dye stuff is used for about 15-120 minutes, 30-90 minutes, 45-75 minutes or about 60 minutes. Alternatively, piece dyeing can be performed with the process described above, using a dyeing vat and a recharge vat.

After dyeing, the dye bath solution is removed and the yarn is contacted with the ferrous sulfate solution disclosed above. The ferrous sulfate solution is used at about 160 to about 210° F., about 170-about 205° F., about 180-about 200° F. or about 190° F. The ferrous sulfate solution is used to fix the dye to the yarn for about 15-120 minutes, 30-90 minutes, 45-75 minutes or about 60 minutes. After fixation, the ferrous sulfate solution is removed.

After fixation with the ferrous sulfate solution, the fabric may be measured to confirm color shade match, washed, dried and inspected. A final color shade check can be performed if desired.

The various dyes used in the present invention are known to one of ordinary skill in the art. They include, for example, indigo, madder, cochineal, cutch, osage, logwood, myrobalan, hematine, pomegranate and chestnut. Powdered and/or liquid dyes are available from suppliers known in the art (for example, Botanical Colors, Seattle Wash.; Couleurs de Plantes, Rochefort, France). Powdered dyes require solubilization before use. Vigorous mixing may be required to dissolve the powdered dye into solution. Liquid dyes may be provided as a concentrate. Liquid dyes and solubilized powdered dyes may need to be adjusted to a desired concentration prior to use by adding water or by concentrating by methods known in the art. Other ingredients may be required as components of the dyestuff solution prior to use. Other ingredients may include, for example, surfactants, calcium carbonate, etc. The present invention is not limited by the nature of other ingredients that may be used in the mordant, dyeing or fixing steps disclosed herein. In other embodiments, the mordant, dye and fixative (ferrous sulfate) compositions given herein may be interpreted as “comprising,” “consisting essentially of” or “consisting of” the ingredients as listed.

Filtration of the natural dyestuff solution may be required. Dyes may need to be filtered to remove impurities and any undissolved dye particles. Filtering can be performed with filter materials having between 100 and 1000 nm (nanometer) porosity, 250-750 nm porosity, and 350-650 nm porosity. One of skill in the art can determine if filtering is necessary by, for example, checking for sediment in the dyestuff solution or by filtering samples of the dyestuff solution to check for impurities.

The use of spectrophotometry enables the accurate measurement of the reflectivity of the material being dyed. The results are compared to one of several standards for such measurement. The standard called C.I.E. Lab (C.I.E. Lab [CIELAB] is a color space standard established by the International Commission on Illumination) is the most common and the one used herein. An initial measurement of the desired color material is made and called the ‘Aim’ or ‘Target.’ Dyed samples of materials are measured to determine how near to the target they are.

In the process defined herein the measurements of both the dye bath and the yarn or fabric are recorded continually. The results are converted with a formula to provide what is called a Δ E (delta E) which indicates how far from the aim that the result is. A process limit is set to result in <1.5 ΔE (for reference, a result of <1 ΔE is not perceivable by most humans, while a result of 1.5 ΔE is considered barely perceptible).

The dyeing process will now be explained as illustrated in FIG. 1. FIG. 1 represents only one of many possible configurations of the dyeing apparatus suitable for use with the present invention, others of which will be evident to one of skill in the art based on the teachings of this specification.

Now, turning to FIG. 1, two vats, tanks or kiers are shown. The right hand kier is the recharge kier. The recharge kier has a viewing port, a spectrophotometer (the second spectrophotometer), a drain at the bottom of the kier and an inlet from the dye kier located about two-thirds of the way up on the side. The top is hinged and secured by, for example, one or more nuts, latches or other suitable securing device.

The dyestuff solution (bath) leaves the recharge kier by the drain and enters the dyeing kier (the left hand kier in the figure) through the center perforated tube. The dyestuff flows through the perforations in the perforated tube and through the yarn package. Both the color and shade of the yarn is monitored with the spectrophotometer for measuring yarn color (the first spectrophotometer). The dyestuff solution is then circulated back to the recharge kier where it will be recharged or allowed to run to dye depletion depending on the readings from the first and second spectrophotometers. The top of the dyeing kier is also hinged and secured similarly to the top of the recharge kier.

Not seen in the figure are 1) holding containers and associated plumbing for compositions necessary to recharge the dyestuff (e.g., dyestuff solution or concentrate), if needed, 2) a computer for analyzing data received from the first and the second spectrophotometers to efficiently monitor and control the dyeing process, 3) plumbing between the two tanks, 4) an apparatus for installing and removing the yarn package from the dyeing kier, 5) pumps, etc.

All ranges given herein are inclusive of all values within the given range. For example, the range of 15-120 minutes includes all values from 15 to 120, inclusive. Thus, for example, the value 35 minutes finds support in the present specification even though it is not specifically mentioned.

EXEMPLIFICATION Example 1 Dyeing Chocolate (Brown) Color

This example provides one specific procedure used to mordant and dye wool yarn. One of ordinary skill in the art, when provided with the teachings of this specification, will be able to modify the procedure with regard to other dye colors and fibers (materials).

-   -   Prepare dyeing vat by adding clean water at ˜190° F.     -   Add mordant chemicals per formula based on % of WOG         -   15% Aluminum Sulfate         -   6% cream of tartar     -   Add material to be dyed     -   Contact material with mordant solution for ˜60 min while         maintain temperature at ˜190° F.         -   Drain mordant solution; keep material wet     -   Add dye per formula based on % of WOG         -   2.5% Logwood         -   10% Cutch         -   0.5% Madder         -   1% calcium carbonate     -   Maintain temperature of ˜190° F.         -   Run dyeing process until spectrophotometer readings indicate             target color and shade are obtained (approx. 30 minutes).         -   drain dye solution     -   Add 3% solution of iron salts (ferrous sulfate) at ˜190° F.     -   Run process for ˜30 min.     -   Remove material, wash in warm water with soap and softener, dry.     -   Inspect

Example 2 Other Dye Colors

The general procedure outlined above in Example 1 can be used with minor modification with regard to other dye colors. One of ordinary skill in the art, provided with the teachings of this specification, will be able to adapt the procedure above without undue experimentation. Dye formulations for numerous other colors are provided below. All percents are approximate within ±20% and may be modified by one of skill in the art as desired. For example, different lots of dye or dye from different suppliers may require minor adjustments in the amounts of dye used. All formulas are based on percent of WOG (weight of goods) to be dyed unless otherwise noted. Mordant formulas are also noted below. Other dye formulations can be developed by one of ordinary skill in the art when provide with the teachings of this specification

Sage

-   -   Mordant     -   15% Aluminum Sulfate     -   6% Cream of Tartar     -   Dye     -   1.5% Hermatine HS or Logwood     -   3.5% Fustic or Osage

French Madder

-   -   Mordant     -   15% Aluminum Sulfate     -   6% Cream of Tartar     -   Dye     -   6% French Madder or 15% India Madder

Madder Red

-   -   Mordant     -   20% Aluminum Sulfate     -   5% Cream of Tartar     -   Dye     -   7% Madder Red or 30% India Madder     -   4% Calcium Carbonate

Rock Salt

-   -   Mordant     -   20% Aluminum Sulfate     -   5% Cream of Tartar     -   Dye     -   0.5% Logwood     -   0.25% Goldenrod

Plum

-   -   Mordant     -   20% Aluminum Sulfate     -   5% Cream of Tartar     -   Dye     -   10% Cochineal

Berry

For dyeing cotton

-   -   Mordant     -   10% Aluminum Acetate     -   Dye     -   7% Cochineal

Black

-   -   Mordant     -   20% Aluminum Sulfate     -   5% Cream of Tartar     -   Dye     -   12% Logwood     -   7.5% cutch     -   5% Fustic     -   7% iron

Pewter

-   -   Mordant     -   20% Aluminum Sulfate     -   5% Cream of Tartar     -   Dye     -   0.6% Longwood or Hematine     -   0.25% Chestnut     -   0.2% Pomegranite

Goldenrod

For dyeing cotton

-   -   Mordant     -   15% Aluminum Acetate     -   Dye     -   10% Goldenrod

Salmon

-   -   Mordant     -   20% Aluminum Sulfate     -   5% Cream of Tartar     -   Dye     -   10% Quebracho red

Indigo

Indigo does not generally require use of a mordant and the pH of the dye bath is about 12 or greater. Use of the ferrous sulfate step is optional.

-   -   Dye—grams per gallon of dye bath     -   NaOH (Sodium hydroxide) 1.2 gams     -   H₂S (Hydrogen sulfide) 9.0 gams     -   Indigo dye 11 grams 

We claim: 1) A process for dying yarn produced from a natural fiber using a natural dyestuff, the process comprising: a) providing a loosely wound yarn package having a yarn density of less than about 0.85 g/cm³; b) providing a natural dyestuff solution; c) providing a tank that will accommodate the yarn package and an initial volume of the natural dyestuff solution; d) providing a yarn package spectrophotometer and a natural dyestuff solution spectrophotometer; e) contacting the yarn package and the initial volume of natural dyestuff solution within the tank under conditions appropriate for uptake of the natural dyestuff by the yarn; f) monitoring absorbance of the yarn package by the yarn package spectrophotometer and the natural dyestuff solution by the natural dyestuff solution spectrophotometer; g) supplementing the initial volume of natural dyestuff solution with an appropriate quantity of the natural dyestuff solution, as needed, to achieve a condition wherein the yarn package spectrophotometer detects absorbance at a desired wavelength and the natural dyestuff solution spectrophotometer detects absorbance consistent with a substantially depleted natural dyestuff solution; h) replacing the dyestuff solution with a solution comprising ferrous sulfate at a concentration of about 1% to 8% by weight of the dry weight of goods (WOG) to be dyed; and i) contacting the yarn package with the ferrous sulfate comprising solution for a period of time suitable to fix the dyestuff to the fibers. 2) The process of claim 1, wherein the yarn package is contacted with a mordant solution prior to being contacted with the dyestuff solution and wherein the mordant solution is removed before the yarn package is contacted with the dyestuff solution. 3) The process of claim 1, wherein the natural fiber is selected from the group consisting of wool or cotton. 4) The process of claim 1, wherein the natural dyestuff is selected from the group consisting logwood, cochineal, madder, cutch, myrobalan, hematine, pomegranate, and chestnut. 5) The process of claim 1, wherein the ferrous sulfate solution is at a concentration of about 2% to 6% by weight of the dry WOG to be dyed. 6) The process of claim 1, further comprising filtering the natural dyestuff solution of step b) prior to step e). 7) The process of claim 6, wherein the natural dyestuff solution is filtered through a 100-1000 nm filter. 8) A process for dying fabric produced from a natural fiber using a natural dyestuff, the process comprising: a) providing a natural dyestuff solution; b) providing a tank that will accommodate the fabric and an initial volume of the natural dyestuff solution; c) providing a fabric spectrophotometer and a natural dyestuff solution spectrophotometer; d) contacting the fabric and the initial volume of natural dyestuff solution within the tank under conditions appropriate for uptake of the natural dyestuff by the yarn; e) monitoring absorbance of the fabric by the fabric spectrophotometer and the natural dyestuff solution by the natural dyestuff solution spectrophotometer; f) supplementing the initial volume of natural dyestuff solution with an appropriate quantity of the natural dyestuff solution, as needed, to achieve a condition wherein the fabric spectrophotometer detects absorbance at a desired wavelength and the natural dyestuff solution spectrophotometer detects absorbance consistent with a substantially depleted natural dyestuff solution; g) replacing the dyestuff solution with a solution comprising ferrous sulfate at a concentration of about 1% to 8% by weight of the dry weight of goods (WOG) to be dyed; and h) contacting the fabric with the ferrous sulfate comprising solution for a period of time suitable to fix the dyestuff to the fibers. 9) The process of claim 8, wherein the fabric is contacted with a mordant solution prior to being contacted with the dyestuff solution and wherein the mordant solution is removed before the fabric is contacted with the dyestuff solution. 10) The process of claim 8, wherein the natural fiber is selected from the group consisting of wool or cotton. 11) The process of claim 8, wherein the natural dyestuff is selected from the group consisting logwood, cochineal, madder, cutch, myrobalan, hematine, pomegranate, and chestnut. 12) The process of claim 8, wherein the ferrous sulfate solution is at a concentration of about 2% to 6% by weight of the dry WOG to be dyed. 13) The process of claim 8, further comprising filtering the natural dyestuff solution of step b) prior to step e). 14) The process of claim 13, wherein the natural dyestuff solution is filtered through a 100-1000 nm filter. 15) The process of claim 8, wherein the fabric is selected from a group consisting of woven and non-woven fabric. 